The GREEN RESCUE: a ‘green’ experimentation to clean old varnishes on oil paintings

In cultural heritage, several initiatives are promoted to transfer the green chemistry in replacing traditional and toxic methods and products, and in ensuring safety of both artworks and restorers during cleaning operations. This study is aimed to establish the validity of new green solvents to replace toxic solvents, commonly used, to remove old paint varnishes. In particular, the research is focused on the use of acetals to remove old varnishes paintings. The acetals are common functional groups in natural products which are generated by reactions between alcohols and aldehydes. The tests were performed on four different resins (DAMAR, RETOUCHER, PVA and PMMA). Several samples were prepared to reproduce the common stratigraphy succession of the oil painting. The performances of the solvents were monitored by visible light/UV light, photography and optical microscopy, spectro-colorimetric analysis. Then, FTIR spectra of the cleaned surface have been acquired to detect the residues after cleaning.